1. Field of the Invention
This invention relates to a pedal propulsion system for powering a transportation conveyance particularly a relatively light weight water craft such as a canoe, boat and the like. The system has a portable support frame such that it is adaptable in the transportation conveyance. The support frame includes a seat for the operator to sit therein to operate the system with ease and comfort for driving the transportation conveyance.
2. Background of the Invention
Pedal propulsion systems are commonly employed for driving a boat. Most of the present propulsion systems are integrally built into the boat so that it is not removable from the latter. Thus it is particularly not convenient to transport the boat having a built-in pedal propulsion system.
In a pedal propulsion system, pedals mounted to a rotary shaft of a sprocket are operative to rotate the sprocket which is coupled by a continuous chain or a gear assembly for delivering the power to the driving device of a transportation conveyance. The sprocket has teeth formed on its peripheral circular edge to engage with links or loops in the chain or alternatively with a gear assembly which also engages with a toothed drive wheel to provide the rotational movement for the transportation conveyance. When a pedal propulsion system is used in a water craft for driving its propeller, the rotational movement of the toothed drive wheel must be converted for 90 degrees in order to rotate the propeller of the water craft. Alternatively, a gear assembly or similar mechanical linkage is employed to change the rotational movement of the sprocket for 90 degrees for the same purpose. The efficiency of a gear assembly or mechanical linkage is low due to friction and mechanical losses. Also, such propulsion systems effectively employ a pushing action for rotating the propeller drive of the water craft, which are inefficient and noisy in operation. The rotation speed of the propeller is also limited by the mechanical ratio between the sprocket and the rotational movement of the conversion wheels and the engagement between the chain and the sprocket or the gear assembly. Furthermore, such systems require high maintenance in sustaining their operation.